The present invention relates to a surgical instrument for moving a bone portion relative to another bone portion. More particularly, the present invention relates to a surgical instrument for moving a vertebra relative to another vertebra.
It is known to secure a fixation rod relative to a first vertebra for supporting a second vertebra that has moved away from, or slipped relative to, a desired position. An implant is attached to the second vertebra. The second vertebra is moved relative to the first vertebra so that the implant may be secured to the fixation rod.
A conventional surgical instrument for moving the second vertebra relative to the first vertebra for securing the implant to the fixation rod includes an instrument for attaching to the implant in the second vertebra. An outwardly extending flange of the instrument supports a corkscrew device. When supported in the flange, a distal end of the corkscrew device may be driven against the fixation rod. Rotation of the corkscrew device relative to the instrument drives the fixation rod into the implant in the second vertebra. An implant plug is introduced into the implant through a cannulation in the instrument. The implant plug secures the implant to the rod so that the second vertebra becomes fixed relative to the first vertebra.
The present invention relates to a surgical instrument for moving a first bone portion relative to a second bone portion. The surgical instrument comprises first and second devices. The first device includes an actuatable clamp for clamping on a fastener fixed to the first bone portion and a threaded carriage that is movable axially relative to the clamp in a direction away from the first bone portion when subjected to a predetermined axial load. The second device includes a threaded portion adapted for threaded engagement with the carriage of the first device and an end portion for supporting a member which engages the fastener fixed to the first bone portion and secures a rod connected to the second bone portion to the fastener. The end portion is adapted for pressing the member against the rod. Relative rotation between the first and second devices during threaded engagement of the carriage of the first device and the threaded portion of the second device causes relative axial movement between the second device and the carriage of the first device. The carriage is stationary relative to the clamp of the first device when a force necessary to produce relative movement between the first and second bone portions is below the predetermined axial load so that relative rotation between the first and second devices moves the clamp and the fastener fixed to the first bone portion and the first bone portion relative to the second bone portion and relative to the rod.
According to another aspect, the present invention relates to a surgical instrument for moving a first bone portion of a body relative to a second bone portion of the body. The surgical instrument comprises a cannula for forming a passage into the body and for defining an operative space adjacent the first and second bone portions. A first device is extendable through the passage formed by the cannula. The first device includes an actuatable clamp for clamping on a fastener fixed to the first bone portion and a threaded carriage that is movable axially relative to the clamp in a direction away from the first bone portion when subjected to a predetermined axial load. A second device is also extendable through the passage formed by the cannula. The second device includes a threaded portion adapted for threaded engagement with the carriage of the first device and an end portion for supporting a member which engages the fastener fixed to the first bone portion and secures a rod connected to the second bone portion to the fastener. The end portion is adapted for pressing the member against the rod. Relative rotation between the first and second devices during threaded engagement of the carriage of the first device and the threaded portion of the second device causes relative axial movement between the second device and the carriage of the first device. The carriage is stationary relative to the clamp of the first device when a force necessary to produce relative movement between the first and second bone portions is below the predetermined axial load so that relative rotation between the first and second devices moves the clamp and the fastener fixed to the first bone portion and the first bone portion relative to the second bone portion and relative to the rod.
According to yet another aspect, the present invention relates to a surgical instrument for threadedly connecting a member and a fastener. The surgical instrument comprises a first device and a second device. The first device includes an actuatable clamp for clamping on the fastener and a threaded carriage that is movable axially relative to the clamp in a direction away from the fastener when subjected to a predetermined axial load. The second device includes a threaded portion adapted for threaded engagement with the carriage of the first device and an end portion for supporting the member to be threadedly connected to the fastener. Relative rotation between the first and second devices during threaded engagement of the carriage of the first device and the threaded portion of the second device causes relative axial movement between the second device and the carriage of the first device. The carriage moves axially away from the fastener that is clamped by the clamp of the first device when a force necessary to threadedly connect the member that is supported on the end portion of the second device and the fastener exceeds the predetermined axial load so that the member is rotated relative to the fastener but is not moved axially relative to the fastener in response to relative rotation between the first and second devices. The carriage is stationary relative to the fastener that is clamped by the clamp of the first device when the force necessary to threadedly connect the member that is supported on the end portion of the second device and the fastener is below the predetermined axial load so that relative rotation between the first and second devices results in the member being threadedly connected to the fastener.